尾插法-实现链表反转（有点bug，以后再来研究下）

def func2(head):
    p = head.next
    while p.next:
        q = p.next
        p.next = q.next  # 重点
        head.next = q
        q.next = p

    p.next = head
    head = head.next
    p.next.next = None
    return head

"""
    测试用例
"""
#节点定义
class LNode:
    def __init__(self, x):
        self.val = x
        self.next = None

#测试用例
if __name__ == '__main__':
    l1 = LNode()
    l1.next = LNode()
    l1.next.next = LNode()
    l1.next.next.next = LNode()
    l1.next.next.next.next = LNode()
    print(l1.val, l1.next.val, l1.next.next.val, l1.next.next.next.val,l1.next.next.next.next.val)
    #l = reverse_link(l1)
    l = func2(l1)
    print(l.val, l.next.val, l.next.next.val,l.next.next.next.val,l.next.next.next.next.val)